San Diego -LRB- CNN -RRB- -- Some elections are fueled by passion . Others are guided by a sense of urgency . This one seems to be driven by ambivalence .

That is where we 're at as we near Tuesday 's Iowa caucuses , the kickoff to the voting portion of the 2012 election . According to the polls in the Hawkeye State , Ron Paul and Mitt Romney are virtually tied for the lead , each with no more than a quarter of the vote .

A new CNN/Time/ORC poll finds that Romney has 25 % and Paul has 22 % , with Rick Santorum , Newt Gingrich and Rick Perry each in the teens .

GOP officials would like to convince Americans that they have an embarrassment of riches on their hands , but many of us can see that they 're only half right . It 's just an embarrassment .

A big part of the Republicans ' problem is having a `` front-runner '' who ca n't seem to get out in front . Many voters feel as if the choice has already been made for them , and they 're not having any of it .

On a recent trip to Washington , I was reminded again that the inside-the-Beltway media and the Republican establishment have ordained Romney the party 's presidential nominee and all but declared that the voting is just a formality .

Yet , someone forgot to tell the voters , who elevate one candidate after another from the `` anybody but Romney '' pile while keeping the former Massachusetts governor trapped under a 25 % ceiling in the polls . As recently noted by The Wall Street Journal , a recent Gallup poll of Republicans put support for Romney at 24 % , and last month , his level of support floated between 22 % and 25 % .

It 's hard to see how Romney could cobble together a string of second-place finishes , with a possible win in New Hampshire , and wind up as a credible contender for the general election . And even if he does somehow wind up being the nominee , it 's even harder to imagine that the more than three-fourths of Republicans who were thoroughly uninspired by him just a few months earlier would suddenly get excited enough to turn out and vote .

In fact , even in this late hour , Republican thought leaders such as William Kristol , publisher of the Weekly Standard , are still suggesting that another Republican candidate could enter the race . That is not likely to happen , but the fact that some people would like it to tells us a lot about a level of dissatisfaction with the current crop of GOP prospects .

The grass is n't any greener for Democrats . While they have the advantage of knowing who their nominee will be , they also have to contend with the same difficult task that the Republicans face : energizing the base to support the candidate .

Many of those who voted for Barack Obama in 2008 do n't seem all that eager to give him an encore . He lost much of his support from independents early on , but he also has an enthusiasm gap developing with liberals who think the president lacks courage and caves in to Republicans too easily .

According to a new poll by the Salt Lake Tribune , while most Democrats want to re-elect Obama , one in five of them are n't so sure . Just 37 % of those surveyed -- Republicans , Democrats and independents -- are certain they want to give Obama another term . And , despite all the campaigning up to this point , nearly 20 % of voters are still undecided about whom to support .

To be re-elected , Obama needs to recapture the support of two groups of voters : young people and Latinos . Unfortunately for Democrats , he 's not doing a good job of inspiring either .

Both groups still support Obama , and they certainly prefer him to every possible Republican alternative . The problem is the same kind of enthusiasm gap that Romney is facing with Republican voters . While 18-to-29 year-old Americans remain solidly in the Democratic camp , only 49 % of them approve of Obama 's job performance , according to a survey by the Pew Research Center . That 's a 23 point drop since February 2009 .

Something similar is happening with Latino voters , many of whom are deeply disillusioned -- even wounded -- by Obama 's broken promise to fix the immigration system combined with his heavy-handed deportation policies that have resulted in the removal of more than 1.2 million people in less than three years .

According to a new Ipsos-Telemundo poll , the president 's support among Latinos continues to plummet . In April 2009 , 86 % of Latinos approved of Obama 's job performance . Today , it 's only about 56 % . According to an analysis done by Ipsos , that drop suggests that , `` the disillusion among Latinos is more pronounced than among the general public . ''

Add all this up , and this could be an election with one of the lowest turnouts in history -- for Republicans and Democrats . Voters are sending a message that both parties need to heed : `` Do n't just tell me I need to vote for your candidate . Give me something worth voting for . ''

The opinions expressed in this commentary are solely those of Ruben Navarrette Jr. .

@highlight

Ruben Navarrette : We 're about to see the start of the voting for Election 2012

@highlight

He says voters in both parties are ambivalent about the choices

@highlight

GOP ca n't seem to crown a front-runner ; liberals lukewarm on Obama , he says

@highlight

Navarrette : Many people may choose not to vote , unless candidates rise to the occasion